Systems and methods of adjusting bass levels of multi-channel audio signals

Patent metadata

Field	Value
Publication number	US-11700501-B2
Application number	US-202017135358-A
Country	US
Kind code	B2
Filing date	Dec 28, 2020
Priority date	Mar 21, 2018
Publication date	Jul 11, 2023
Grant date	Jul 11, 2023

Abstract

Systems and methods for adjusting bass levels of a multi-channel audio signal include, among other features, (i) receiving the multi-channel signal via a playback device; (ii) separating, from the multi-channel signal, low-frequency signals comprising frequencies less than a threshold frequency; (iii) determining electrical energies of the low-frequency signals; (iv) determining a first energy by summing the electrical energies of the low-frequency signals; (v) consolidating the low-frequency signals into a consolidated low-frequency signal; (vi) determining a second energy by determining an electrical energy of the consolidated low-frequency signal; (vii) generating a gain-adjusted low-frequency signal by adjusting a gain of the consolidated low-frequency signal based on both (a) the first energy and (b) the second energy; (viii) generating a gain-adjusted multi-channel signal by mixing the gain-adjusted low-frequency signal back into the multi-channel signal; and (ix) using the gain-adjusted multi-channel signal to play back gain-adjusted multi-channel audio content via the playback device.

First claim

The invention claimed is:

1. A playback device comprising:
a plurality of audio drivers;
one or more processors;
tangible, non-transitory, computer-readable media storing instructions executable by the one or more processors, wherein the instructions, when executed, cause the playback device to perform operations comprising:
receiving a multi-channel audio signal comprising a set of audio channels;
for each channel in the set of audio channels, applying a low pass filter to the channel to obtain a low-frequency component of the channel comprising audio information below a threshold frequency;
combining the low-frequency component of each channel into a consolidated low frequency signal;
adjusting a gain of the consolidated low frequency signal to generate a gain-adjusted consolidated low frequency signal;
for each channel in the set of audio channels, mixing the gain-adjusted consolidated low frequency signal with audio content of the channel above the threshold frequency to generate a gain-adjusted channel;
playing the individual gain-adjusted channels via the plurality of audio drivers;
wherein the set of channels in the multi-channel audio signal comprises a left-channel audio signal, a center-channel audio signal, and a right-channel audio signal, and wherein for each channel in the set of audio channels, applying a low pass filter to the channel to obtain a low-frequency component of the channel comprising audio information below a threshold frequency comprises:
low pass filtering the left-channel audio signal to obtain a low-frequency component of the left-channel audio signal comprising audio information below the threshold frequency;
low pass filtering the right-channel audio signal to obtain a low-frequency component of the right-channel audio signal comprising audio information below the threshold frequency; and
low pass filtering the center-channel audio signal to obtain a low-frequency component of the center-channel audio signal comprising audio information below the threshold frequency.

2. The playback device of claim 1 , wherein adjusting a gain of the consolidated low frequency signal to generate a gain-adjusted consolidated low frequency signal comprises:
for each channel in the set of audio channels, determining an electrical energy of the low frequency component of the channel;
determining a first energy representing a sum of the electrical energies of the low frequency components of the channels in the set of audio channels;
determining a second energy representing an electrical energy of a sum of the low frequency components of the channels in the set of audio channels; and
generating the gain-adjusted consolidated low frequency signal based on both (i) the first energy and (ii) the second energy.

3. The playback device of claim 2 , wherein adjusting a gain of the consolidated low frequency signal to generate a gain-adjusted consolidated low frequency signal comprises adjusting a gain of the consolidated low frequency signal according to:
G=E 1 /E 2 ,
wherein G is the gain adjustment of the consolidated low frequency signal, E 1 is the first energy, and E 2 is the second energy.

4. The playback device of claim 1 , wherein adjusting a gain of the consolidated low frequency signal to generate a gain-adjusted consolidated low frequency signal reduces a volume of any audio content that includes the gain-adjusted consolidated low frequency signal that is played by the playback device.

5. The playback device of claim 1 , wherein each channel in the multi-channel audio signal corresponds to a sound axis, and wherein playing the individual gain-adjusted channels via the plurality of audio drivers comprises:
playing each gain-adjusted channel via a sound axis corresponding to the channel.

6. The playback device of claim 1 , wherein the plurality of audio drivers includes a first audio driver and a second audio driver, and wherein a value of the threshold frequency is based on a distance between the first and second audio drivers.

7. The playback device of claim 6 , wherein the distance between the first and second audio drivers is an odd-integer multiple of a quarter-wavelength of the threshold frequency.

8. Tangible, non-transitory, computer-readable media storing instructions executable by one or more processors, wherein the instructions, when executed, cause a playback device to perform operations comprising:
receiving a multi-channel audio signal comprising a set of audio channels;
for each channel in the set of audio channels, applying a low pass filter to the channel to obtain a low-frequency component of the channel comprising audio information below a threshold frequency;
combining the low-frequency component of each channel into a consolidated low frequency signal;
adjusting a gain of the consolidated low frequency signal to generate a gain-adjusted consolidated low frequency signal;
for each channel in the set of audio channels, mixing the gain-adjusted consolidated low frequency signal with audio content of the channel above the threshold frequency to generate a gain-adjusted channel;
playing the individual gain-adjusted channels via a plurality of audio drivers;
wherein the set of channels in the multi-channel audio signal comprises a left-channel audio signal, a center-channel audio signal, and a right-channel audio signal, and wherein for each channel in the set of audio channels, applying a low pass filter to the channel to obtain a low-frequency component of the channel comprising audio information below a threshold frequency comprises:
low pass filtering the left-channel audio signal to obtain a low-frequency component of the left-channel audio signal comprising audio information below the threshold frequency;
low pass filtering the right-channel audio signal to obtain a low-frequency component of the right-channel audio signal comprising audio information below the threshold frequency; and
low pass filtering the center-channel audio signal to obtain a low-frequency component of the center-channel audio signal comprising audio information below the threshold frequency.

9. The tangible, non-transitory computer readable media of claim 8 , wherein adjusting a gain of the consolidated low frequency signal to generate a gain-adjusted consolidated low frequency signal comprises:
for each channel in the set of audio channels, determining an electrical energy of the low frequency component of the channel;
determining a first energy representing a sum of the electrical energies of the low frequency components of the channels in the set of audio channels;
determining a second energy representing an electrical energy of a sum of the low frequency components of the channels in the set of audio channels; and
generating the gain-adjusted consolidated low frequency signal based on both (i) the first energy and (ii) the second energy.

10. The tangible, non-transitory computer readable media of claim 9 , wherein adjusting a gain of the consolidated low frequency signal to generate a gain-adjusted consolidated low frequency signal comprises adjusting a gain of the consolidated low frequency signal according to:
G=E 1 /E 2 ,
wherein G is the gain adjustment of the consolidated low frequency signal, E 1 is the first energy, and E 2 is the second energy.

11. The tangible, non-transitory computer readable media of claim 8 , wherein adjusting a gain of the consolidated low frequency signal to generate a gain-adjusted consolidated low frequency signal reduces a volume of any audio content that includes the gain-adjusted consolidated low frequency signal that is played by the playback device.

12. The tang

Assignees

• Sonos Inc

Inventors

• Lehnert Hilmar
• Ramos Aurelio
• Dizon Bob

Classifications

• H04S3/006

  in which a plurality of audio signals are transformed in a combination of audio signals and modulated signals, e.g. CD-4 systems · CPC title

• H04R5/04

  Circuit arrangements, {e.g. for selective connection of amplifier inputs/outputs to loudspeakers, for loudspeaker detection, or for adaptation of settings to personal preferences or hearing impairments (combinations of amplifiers H03F3/68; stereophonic systems H04S)} · CPC title

• H04S2400/07

  Generation or adaptation of the Low Frequency Effect [LFE] channel, e.g. distribution or signal processing · CPC title

• H04R5/02

  Spatial or constructional arrangements of loudspeakers · CPC title

• H04S2400/01

  Multi-channel, i.e. more than two input channels, sound reproduction with two speakers wherein the multi-channel information is substantially preserved · CPC title